\begin{itemize}
\item ``Is running Java a security problem?''  $\to$ Only if you enable
  execution of Java programs in your web browser. Today, there is practically
  no need to run Java from the browser, so you should disable this option (it
  is probably disabled already).  Always keep your JRE up-to-date.

\item ``I am running Windows and I get an error message, `ERROR: JAVA\_HOME is
  set to an invalid directory'.'' $\to$ Probably, deleting the JAVA\_HOME
  environment variable will solve the problem, see the instructions for the
  PATH variable above.

\item ``I want to run SIRIUS on Windows~XP!''  $\to$ Don't.  Running
  Windows~XP on a computer connected to the internet is a security hazzard.
\end{itemize}